Abstract: A rotary valve of a hydraulic power steering gear includes an input-shaft journalled within a sleeve. In the bore of the sleeve, an array of eight axially extending blind-ended slots and an array of two primary and two secondary axially extending return channels are formed. The primary return channels are diametrically opposed, and the secondary return channels are diametrically opposed. The return channels extend to at least one axial extremity of the bore to communicate hydraulic fluid to a return port. Further, the radial depth of the secondary return channels is substantially less than the radial depth of the primary return channels at or near the axial extremity.

Abstract: A low noise rotary valve for a hydraulic power steering gear that offers flexibility in the design of its boost characteristic has inlet ports to receive hydraulic fluid from a pump, return ports to return hydraulic fluid to the pump, and cylinder ports to communicate the hydraulic fluid to left and right-hand cylinder chambers of the hydraulic power steering gear. The valve has an input-shaft with a plurality of axially extending grooves separated by lands. A sleeve that has in its bore an array of axially extending slots that circumferentially align with the lands on the input-shaft is journalled on the input shaft. The interfaces between the coacting input-shaft grooves and sleeve slots define axially extending orifices which open and close when relative rotation occurs between the input shaft and the sleeve. These orifices are ported as a network such that they form primary and secondary hydraulic Wheatstone bridges each having right and left-hand inlet orifices and return orifices.

Abstract: A forging die for forming a steering rack portion having teeth and two longitudinally extending guide faces from a blank. The die comprising first (18) and second (19) die members and four forming elements (52, 53, 54, 55) to converge on the blank. The first forming element (52) being on the second die member (19) for forming the teeth, the second (53) and third (54) forming elements being on the first die member (18) for forming the guide faces. The fourth forming element (55) slidable relative to the first die member (18) for forming a surface of the portion and connected to a first bias means (83, 84) allowing movement of the fourth forming element (55) during forging.

Abstract: Hydraulic valves subjected to a pressure medium in power steering gear include a sleeve journalled on an input shaft, with the sleeve having a torsion bar connected thereto via a driven member. A method of balancing the hydraulic valve includes the steps of inserting the valve into a balanced housing, then determining the neutral position of the input shaft relative to the sleeve. The neutral position is then fixed by rotational connection of the input shaft and torsion bar. The pressure medium used to determine the neutral position is a gaseous medium, and a temporary sealing device adapted to seal the gaseous medium is in contact with the outside surface of the sleeve during determination of the neutral position.

Abstract: A machine for grinding longitudinal troughs in the edges of grooves of a power steering valve input-shaft (4), the input-shaft being supported for rotation on supports (14, 15), a grinding wheel (30) having a contoured periphery corresponding in cross-section to the cross-section of the trough (5), the grinding wheel being relatively movable towards the input-shaft to some predetermined depth of engagement therewith and to be retracted therefrom and being movable axially relative to the input-shaft to form a longitudinal trough (5) to produce oblique terminations of the trough.

Abstract: A rotary valve having chamfers (26,39) at the groove edges (31) of its input shaft (10) which, in conjunction with axially extending troughs (44), form metering edge contours. The chamfers (26,39) and troughs (44) at the edges (31) of the grooves (18a,18b) interacting with sleeve slots (19) to reduce valve hiss and linearise the boost characteristic of the valve.

Abstract: Apparatus for machining an angularly disposed array of slots (FIG. 7) concentric with the axis (85) of a bore of a valve sleeve (1) which has a sleeve holder (3) which is rotatably indexed for locating the arcuate position of each slot of the array, a cutting tool (5) positioned on the apparatus to cut a slot in the bore of the sleeve at each indexed location and a boring device (80, 81, 82, 83, 90) for forming the bore co-axially with the array of slots; the operation of the cutting tool (5) and boring device (80, 81, 82, 83, 90) taking place while the sleeve (1) is mounted in the one orientatioln in the holder (3).

Abstract: A mechanical function generating mechanism for a front and rear wheel steered vehicle is operable to generate a rear steer angle output as a function of front steer angle and vehicle speed inputs. The mechanism has a three dimensional cam with a cam surface and a contacting follower. The cam surface is traversed relative to the follower in a first direction in accordance with the front steer angle input and is traversed relative to the follower in a second direction substantially at right angles to the first direction according to the vehicle speed input. The follower is constrained to move in a third direction, determined by the shape of the cam surface, substantially normal to the first and second directions to generate the rear steer angle output.

Abstract: A machine for machining blind-ended slots longitudinally disposed within the bore of a sleeve (1) held in a chuck (4) in a work holding spindle (5) indexable about a rotational axis, a reciprocable cutting tool (2) mounted on a cutting spindle (12) the axis of which is offset from and at right angles to the rotational axis of the work holding spindle (5) in which the cutting tool (2) executes a succession of progressively deeper cutting and subsequent return strokes so that a number of blind-ended slots are machined in the sleeve (1) characterized in the provision of a slidable support (6) for the work holding spindle (5) to slide the work holding spindle (5) axially relative to the cutting spindle (12) a distance such that the cutting tool is radially and axially clear of the bore when all slots are machined, cutting strokes of the cutter being discontinued.

Abstract: A front and rear wheel steering system for a vehicle has a front steer system (23, 25) and a rear steer system (21, 22) with a rear steer controller (12) functioning to set the rear steer angle in dependence upon front steer angle and vehicle speed. A low load capacity feedback device (14) functions to maintain a predetermined relationship between front and rear wheel steer angles with an overload protector (74, 77, 78) protecting the feedback device (14) from damage due to the application of loads above a predetermined level.

Abstract: A machine for grinding the outer metering edge contours (26) on the edges of the axially extending grooves (18) of a power steering gear input-shaft (10) in which a substantially cylindrical grinding wheel (40) whose working surface is dressed parallel to the axis of the input-shaft (10) effects the grinding, the distance between the input-shaft (10) and the grinding wheel (40) being cyclically increased and decreased several times during each revolution of the input-shaft (10) in such a manner that each outer metering edge contour (26) so ground has a form which is a mirror image of the form of at least one other outer metering edge contour (26) around the outside periphery of the input-shaft (10), characterized in that the angular velocity of the input-shaft (10) is varied cyclically in a manner co-ordinated with the cyclic increase and decrease of the distance between the input-shaft (10) and the grinding wheel (40) thereby substantially reducing the peak rate of stock removal per unit time compared with t

Abstract: Apparatus for forming an array of elongate slots in the bore of a valve sleeve (1) where the slots are cut in the bore by an arcuately movable cutting tool (5) mounted on the apparatus and the movement of the cutting tool (5) to form the length and depth of each slot is under the control of a desmodromic cam (12, 13) and a variable offset between the pivotal axis (8) of the cutting tool (95) and the pivotal axis (10) of the followers (15, 16) contacting the cam (12, 13).

Abstract: A hydraulic power steering rotary valve of generally conventional construction characterized in that the on-center characteristics of the valve are governed by an arrangement of rolling elements and notched elements arranged to produce a detent action between the input shaft and the sleeve or driven member, the rolling elements rolling between opposite surface contours of a pair of opposed notched elements, the contours each including a convex surface the shape of which is such that a centering torque between the input shaft and the sleeve or driven member is produced which decreases for increasing amounts of rotation away from a neutral condition of the rotary valve.

Abstract: A rotary valve (1) for hydraulic power steering of vehicles with arcuate slots (9,10) in the sleeve (2) and slots (11) in input-shaft (3) of the valve (1) where some of the slots (10) in the sleeve (2) are formed to provide hydraulic fluid return ports (13) axially of the valve (1) between the sleeve (2) and the input-shaft (3) while the axial extent of adjacent sleeve slots (10) and input-shaft slots (11) is the same at their ends remote from the return ports (13).

Abstract: A scanning induction hardening process in which a steel workpiece is surface hardened by progressively traversing its length with an inductor coil energized by an alternating electric current and immediately thereafter quenching the heated portion of the workpiece straightening of bends in the workpiece being surfaced hardened being controlled during the induction hardening process by monitoring the straightness of the workpiece and utilizing information thereby obtained to control the heating and quenching of the workpiece is such a manner that a layer of hardened material of greater thickness is formed on the concave side of any bend in the workpiece such as to produce a straightening moment acting to remove the bend characterized in that the inductor coil is shaped to heat only a portion of the circumference of the work piece, or shaped to concentrate more heat in one portion of the circumference, and the speed of rotation of the work piece is varied to allow the concave side of the work piece to remain in